Vol. 11, Special Issue 12 (2022)

Author(s):
Anju Mariam Joseph, Arya K, Veena Vigneswaran and Thouseem N

Abstract:
Rice (Oryza sativa L.), one of the most important cereal crops, serves as the staple food for over one-third of the world’s population. Susceptibility or tolerance of rice plants to high salinity is a co-ordinated action of multiple stress responsive genes. Introgressing the QTL for salt resistance Saltol into the high yielding variety Sreyas will improve its suitability for cultivation in salinity affected regions. Marker Assisted Backcross Breeding (MABB) can be effectively employed as it helps in eliminating the difficult field level procedure by early screening and identification of tolerant lines carrying the locus. Polymorphism assay of SSR markers was done to select the foreground markers associated with the QTL located on the short arm of chromosome 1 polymorphic between parents and genome wide markers for background selection. Hybridization of the variety Sreyas (MO-22) with the identified salt donor FL478, a source of Saltol QTL induces salt tolerance. F₁ plants were phenotyped in vitro and the survived plants under 12 dS m^-1 (NaCl) were backcrossed with recurrent parent to develop BC₁F₁ generation. More than 200 BC₁F₁ plants were phenotyped in vitro and the survived plants under 12 dS m^-1 (NaCl) were genotyped using polymerase chain reaction and polyacrylamide gel electrophoresis for heterozygosity of the markers linked to Saltol. The plants selected in foreground screening plants were genotyped for background homozygosity with recurrent parent and the BC₁F₁ plants with maximum homozygosity with recurrent parent will be selected and backcrossed with the respective recurrent parents to raise BC₂F₁ generation. The parental population was assayed for foreground polymorphism using 30 SSR markers of which 9 were found to be polymorphic. In case of background polymorphism, of the 200 SSR markers assayed 75 showed polymorphism. F₁ plants phenotyped in vitro and genotyped for heterozygosity regarding all the foreground markers. 12 BC₁F₁ plants were selected to be forwarded to next generations to develop the backcross inbred lines.